Semiconductor integrated circuit (IC) technology has experienced rapid progress including the continued minimization of feature sizes and the maximization of packing density. The minimization of feature size relies on improvement in photolithography and its ability to print smaller features or critical dimensions (CD). However, a photomask used in photolithography may suffer an angle-dependent CD difference, in which pattern features such as lines may have different widths when disposed from different directions. For example, a photomask may have an X-Y CD difference, 45-135 degree CD difference, or any other angle related CD difference. These CD differences often cause lithography patterning degradation, wafer manufacturing quality issues, and even yield concerns.